Rhizospheric bacterial strain Pseudomonas putida and fungal strain Penicillium chrysogenum alleviate Fusarium wilt of tomato by improving key growth attributes

Fusarium oxysporum f. sp. lycopersici, is known to cause Fusarium wilt of tomato. In this study, biocontrol potential of a beneficial bacterium (Pseudomonas putida) and a fungus (Penicillium chrysogenum) were compared, both in vitro and in vivo. Findings of this study reveale the highest mycelial growth inhibition (83%) of F. oxysporum by the application of P. putida, while P. chrysogenum also show a significant inhibition (69%), as compared to the control. Fusarium wilt of tomato seedlings was also significantly reduced by the application of P. putida (83%) and P. chrysogenum (67%). Both P. putida and P. chrysogenum improved seeds germination (82% and 76%, respectively), root length (32% and 11%, respectively), shoot length (35% and 19%, respectively), fresh weight (48% and 18%, respectively) and dry weight (66% and 33%, respectively). A histopathological study revealed severe damage of root and shoot tissues by F. oxysporum. Both biocontrol agents decreased disease infestation by improving chlorophyll and carotenoids attributes, relative water contents and sugar contents and by reducing electrolytic leakage. Application of both inoculants elevated activities of peroxidase (POD), catalase (CAT) and superoxide-dismutase (SOD) enzymes under biotic-stress conditions than their pertinent controls. These biocontrol agents also enhanced pathogen stress tolerance in tomato seedlings by minimizing the production of Malondialdehyde (MDA) and H₂O₂. Findings of this study show the effectiveness of both P. putida and P. chrysogenum in promoting tomato growth and preventing Fusarium wilt, with P. putida being slightly more effective biocontrol agent.